Process and apparatus for manufacturing an electrocatalytic electrode

Abstract

A process and an apparatus for manufacturing electrocatalytic electrodes. The process comprises the steps of immersing a substrate in a plating bath containing metal ions and electrocatalytic material in particles form, such as Ni, NiAl, and CoAl, among others. Electric current is established in the bath inducing a deposition of metal on the substrate by reduction of metal ions and, simultaneously, the cell containing the plating bath is inverted periodically to cause a recurrent migration of the particles of electrocatalytic material, under the effect of gravity, toward the substrate, in order to build-up a layer of electrocatalytic material on the substrate, the particles of the electrocatalytic material being fixed on the substrate by the reduction of metal ions.

We claim: 
     
       1. A process for manufacturing an electrocatalytic electrode, comprising the steps of: placing an electrically conductive substrate in a solution contained in an electrolytic cell, said solution itself containing ions of a metal and dispersed particles of an electrocatalytic material selected from the group consisting of:   (1) Fe;   (2) Ni;   (3) Co;   (4) Cu; and   (5) an alloy of at least two metals, namely a first metal and a second metal, said first metal being selected from the group consisting of: (a) Fe;   (b) Ni;   (c) Co; and   (d) Cu,   said second metal being selected from the group consisting of:   (a) Al;   (b) Zn;   (c) Cd;   (d) Sn; and   (e) Mo,     establishing an electric current in said solution between an anode and a cathode, said substrate constituting said cathode, to thereby induce a deposition of metal on said substrate by reduction of metal ions, said deposited metal forming a binder for retaining particles of said electrocatalytic material on said substrate; and   periodically turning said cell between at least two predetermined positions to cause a recurrent migration of the particles of electrocatalytic material, under the effect of gravity, toward said substrate whereby particles of the electrocatalytic material are captured in said binder.   
     
     
       2. A process defined in claim 1, wherein said metal ions are nickel ions. 
     
     
       3. A process as defined in claim 1, comprising the step of agitating said solution to cause collisions between the particles of electrocatalytic material. 
     
     
       4. A process as defined in claim 1, wherein said electrocatalytic material is constituted by said metal alloy, said process further comprising the step of leaching the particles of electrocatalytic material captured in said binder to remove said second metal therefrom. 
     
     
       5. A process for manufacturing an electrocatalytic electrode, comprising the steps of: placing an electrically conductive substrate in a solution contained in an electrolytic cell, said solution itself containing ions of a metal and dispersed particles of an electrocatalytic material selected from the group consisting of:   (1) Fe;   (2) Ni;   (3) Co;   (4) Cu; and   (5) an alloy of at least two metals, namely a first metal and a second metal, said first metal being selected from the group consisting of: (a) Fe;   (b) Ni;   (c) Co; and   (d) Cu,   said second metal being selected from the group consisting of:   (a) Al;   (b) Zn;   (c) Cd;   (d) Sn; and   (e) Mo,     establishing an electric current in said solution between an anode and a cathode, said substrate constituting said cathode, to thereby induce a deposition of metal on said substrate by reduction of metal ions, said deposited metal forming a binder for retaining particles of said electrocatalytic material on said substrate; and   periodically inverting said cell to cause a recurrent migration of the particles of electrocatalytic material, under the effect of gravity, toward said substrate whereby particles of the electrocatalytic material are captured in said binder.   
     
     
       6. A process as defined in claim 5, wherein said cell is elongated and comprises two ends, and wherein said cell is periodically inverted to cause migration of the particles of electrocatalytic material, under the effect of gravity, from each end of said cell to the other end thereof. 
     
     
       7. A process for producing an electrocatalytic electrode, comprising the steps of: placing an electrically conductive substrate having two generally opposite surfaces in a solution contained in an electrolytic cell, said solution itself containing ions of a metal and dispersed particles of an electrocatalytic material selected from the group consisting of:   (1) Fe;   (2) Ni;   (3) Co;   (4) Cu; and   (5) an alloy of at least two metals, namely a first metal and a second metal, said first metal being selected from the group consisting of: (a) Fe;   (b) Ni:   (c) Co; and   (d) Cu,   said second metal being selected from the group consisting of:   (a) Al;   (b) Zn;   (c) Cd;   (d) Sn; and   (e) Mo,     establishing an electric current in said solution between an anode means and a cathode, said substrate constituting said cathode, to thereby induce a deposition of metal on each surface of said substrate by reduction of metal ions, said deposited metal forming a binder for retaining particles of said electrocatalytic material on said substrate; and   periodically inverting said cell to cause a recurrent migration of the particles of electrocatalytic material, under the effect of gravity, toward each surface of said substrate, whereby particles of the electrocatalytic material are captured in said binder.   
     
     
       8. A process as defined in claim 7, wherein said cell is elongated and comprises two ends, and wherein said cell is periodically inverted to cause a recurrent migration of the particles of said electrocatalytic material, under the effect of gravity, from each end of said cell to the other end thereof. 
     
     
       9. A process as defined in claim 7, wherein said metal ions are nickel ions. 
     
     
       10. A process as defined in claim 7, wherein said anode means includes two anodes, each anode facing a respective one of said surfaces of said substrate, said current establishing step comprising the step of establishing an electric current in said solution between said substrate and each anode. 
     
     
       11. A process as defined in claim 7, comprising the step of agitating said solution to cause collisions between particles of the electrocatalytic material in said solutions. 
     
     
       12. A process as defined in claim 7, wherein said electrocatalytic material is constituted by said metal alloy, said process further comprising the step of leaching said particles of electrocatalytic material captured in said binder to remove said second metal therefrom. 
     
     
       13. An apparatus for producing an electrocatalytic electrode from an electrically conductive substrate immersed in a solution containing ions of a metal and dispersed particles of an electrocatalytic material selected from the group consisting of: (1) Fe;   (2) Ni;   (3) Co;   (4) Cu; and   (5) an alloy of at least two metals, namely a first metal and a second metal, said first metal being selected from the group consisting of:   (a) Fe;   (b) Ni;   (c) Co; and   (d) Cu,   said second metal being selected from the group consisting of:   (a) Al;   (b) Zn;   (c) Cd;   (d) Sn; and   (e) Mo,   said electrode producing apparatus comprising:   a cell itself comprising container means to receive said solution, an anode means in electrical contact with said solution, and means for holding said substrate immersed into said solution, said substrate constituting a cathode;   an electric power source connected to said anode means and to said substrate to establish an electric current in said solution between said anode means and said substrate to thereby induce a deposition of metal on said substrate by reduction of metal ions, said deposited metal forming a binder for retaining particles of said electrocatalytic material on said substrate; and means for periodically turning said cell between at least two predetermined positions to cause a recurrent migration of the particles of electrocatalytic material, under the effect of gravity, toward said substrate whereby particles of the electrocatalytic material are captured in said binder, said anode means comprising a pair of spaced apart anodes, said substrate being mounted between said anodes and comprising two generally opposite surfaces to be coated with electrocatalytic material, each surface being faced by a respective one of said two anodes and wherein each anode is formed with a passage allowing particles of the electrocatalytic material to migrate through said passage.   
     
     
       14. An apparatus for producing an electrocatalytic electrode from an electrically conductive substrate immersed in a solution containing ions of a metal and dispersed particles of an electrocatalytic material selected from the group consisting of: (1) Fe;   (2) Ni;   (3) Co;   (4) Cu; and   (5) an alloy of at least two metals, namely a first metal and a second metal, said first metal being selected from the group consisting of:   (a) Fe;   (b) Ni;   (c) Co; and   (d) Cu,   said second metal being selected from the group consisting of:   (a) Al;   (b) Zn;   (c) Cd;   (d) Sn; and   (e) Mo,   said electrode producing apparatus comprising:   a cell itself comprising container means to receive said solution, an anode means in electrical contact with said solution, and means for holding said substrate immersed into said solution, said substrate constituting a cathode;   an electric power source connected to said anode means and to said substrate to establish an electric current in said solution between said anode means and said substrate to thereby induce a deposition of metal on said substrate by reduction of metal ions, said deposited metal forming a binder for retaining particles of said electrocatalytic material on said substrate; and means for periodically turning said cell between at least two predetermined positions to cause a recurrent migration of the particles of electrocatalytic material, under the effect of gravity, toward said substrate whereby particles of the electrocatalytic material are captured in said binder and further comprising means for agitating the solution in said cell.   
     
     
       15. An apparatus as defined in claim 14, wherein said solution agitating means comprises: an agitator blade mounted in said cell;   shaft means connected to said agitator blade, said shaft means protruding outside said cell;   motor means for driving said shaft means; and   a releasable coupling between said motor means and said shaft means.   
     
     
       16. An apparatus as defined in claim 14, wherein said cell is elongated and comprises two ends, and wherein said cell turning means comprises means for periodically inverting said cell to cause a recurrent migration of the particles of electrocatalytic material, under the effect of gravity, from each end of the cell toward the other end thereof.